Ferrite junction switching circulators are three-port devices used to route RF energy from a first port to a second port, while isolating a third port. If switched to circulate in the opposite direction (generally referred to as clockwise or counter-clockwise directions), then they can route RF energy from the first port to the third port, while isolating the second port. This functionality is used in RF systems such as beam forming networks and switched beam antennas to reconfigure the antenna pattern of the system. In this manner, the switching circulators route the RF energy from a single source to a single radiating antenna element to provide a spot beam hopping function.
To provide more options for beam steering, variable power dividers (VPDs) can be used to route the RF energy from a single source to a plurality of radiating antenna elements with an electronically controllable weighting or ratio of power between the elements. The ratio of the input power distributed to each of the two output ports of a single VPD can be varied essentially anywhere from 0 to 1, with a step size determined by the application's needs. Networks (binary trees) of VPDs are constructed based on the number of radiating antenna elements. VPD applications include satellite and terrestrial, communications and radar, and any other application where electronic beam steering is desired.
Current variable power dividers are either too large, have moving parts that cannot be quickly reconfigured, or cannot be electronically controlled. Typical implementation of electronically controlled VPDs requires 2 power dividers and 2 phase shifters and are therefore quite large (5 to 10 times larger) in comparison to a switching circulator.
Three-port switching circulators can be electronically controlled to provide a variable power division. However, current three-port switching circulator variable power dividers are limited to three output power ratios, typically 0, 0.5, and 1. Some variable power dividers incorporate physical changes to the circulator to provide different ratios other than 0.5 (50/50), but the ratio is varied by physical changes to the dimensions or alignment, so any single implementation is limited to three output ratios.
For the reasons stated above and for other reasons stated below, which will become apparent to those skilled in the art upon reading and understanding the specification, there is a need in the art for improved systems and methods for variable power division.